#include <iostream>
#include <cstring>
#include <iomanip>

using namespace std;

int main()
{
    const int nm_size = 128;
    char user_name[nm_size];
    cout << "input your name: ";
    //setw()保证域宽不会越界
    cin >> setw(nm_size) >> user_name;

    switch (strlen(user_name))
    {
    case 0:
        cout << "hi, user with no name\n";
        break;
    case 1:
        cout << "A 1 character name ?"
            << "Ok, hi"
            << username << "\n";
        break;
    case 127:
        cout << "this is a big name";
    default:
        cout << "Hello" << username << endl;
        break;
    }

    return 0;
}
